The present invention generally relates to a cassette and more particularly, to a tape cassette for use in a recording and reproducing apparatus such as a video tape recorder or the like, and also in various information processing apparatuses, etc.
Recently, tape cassettes of various types or formats closely resembling each other have come to appear on the market, and there have been increasing cases where a tape cassette of one specific type is incorrectly inserted or loaded, for example, into a video tape recorder (referred to as a VTR hereinafter) of a different format by mistake. Accordingly, it has been required to provide the tape cassettes with a means to completely prevent such incorrect insertion as referred to above.
In FIG. 1, there is shown a conventional tape cassette C for use, for example, in a VTR. The tape cassette C generally includes a cassette main body 3 having an upper case 3a and a lower case 3b fitted to each other to define an opening 4 at a front side of said main body 3, tape supply and take-up reels 2 on which is wound a magnetic tape 5 and rotatably incorporated within said main body 3, with the magnetic tape 5 being stretched between said reels along tape slackening preventing members 3e and 3f in said opening 4, and a front cover 6 movably or pivotally mounted on the main body 3 along the opening 4 for selective opening or closing of said opening so as to cover the front face of said magnetic tape when closed.
FIG. 2 shows a front portion of a tape cassette holder 7 in a VTR of a type in which the tape cassette C of FIG. 1 can not be loaded for recording or reproduction. The tape cassette holder 7 has a lateral width larger than the longitudinal length of the tape cassette C, and is provided at its central portion, with a projection 7a for prevention of reverse insertion of a tape cassette capable of being recorded or reproduced by the above VTR in FIG. 2, or insertion of a tape cassette incapable of being recorded or reproduced by said VTR. When a tape cassette of an improper type is to be inserted into the holder 7 by mistake, the projection 7a contacts the front cover 6 of the tape cassette C to obstruct the loading of said tape cassette.
Problems related to the conventional tape cassette C referred to above will be described in more detail with reference to FIGS. 3 to 6.
FIGS. 3 and 4 are fragmentary cross sections showing on an enlarged scale, the portion at the opening 4a of the tape cassette main body 3, while FIGS. 5 and 6 also show fragmentary cross sections at the portion where the projection 7a contacts the tape cassette main body 3 at the opening 4b.
As shown in FIG. 3, in the state where the front cover 6 is closed, the forward edge of a protrusion 6a formed at the lower portion of the front cover 6 is held in contact with the outer edge of the projection 3d on the bottom of the tape slackening preventing member 3f and in line with the bottom of the lower case 3b. In this state, when it is attempted to forcibly insert the tape cassette C into the tape cassette holder 7, the front cover 6 collides with the projection 7a so as to be deformed as shown in FIGS. 4 and 6. However, since the clearance between the upper inner side 6b of the front cover 6 and the front upper side 3c of the upper case 3a is small, said upper inner side 6b and front upper side 3c are brought into contact with each other upon starting of deformation of the front cover 6 downwardly, and thus, such downward deformation of the front cover 6 does not actually take place. Conversely, said front cover 6 is deformed in an upward direction due to the fact that there is no particular member provided for strongly correcting such upward deformation. Therefore, a gap is formed between the underface of the cassette main body 3 and the underface of the front cover 6, and at the opening portion 4b where the main body 3 contacts the projection 7a of the cassette holder 7, said projection 7a is forced into the gap referred to above as shown in FIG. 6.
In the above case, the inner side of the front cover 6 and the protrusion 6a thereof strongly contact the magnetic tape 5, thus resulting in damage to the magnetic tape 5. Moreover, if the tape cassette C is taken out, with the projection 7a of the cassette holder 7 held within the opening 4b, the front cover 6 strongly contacts the projection 7a, inviting such a serious problem as breakage of the front cover 6 in the worst case.
Furthermore, there is also such a problem that, in the case where the front face and underface of the front cover 6 of the tape cassette C collide with the ground or the like due to dropping, the front cover 6 is deformed in the upward direction so that the protrusion 6a contacts the magnetic tape 5, thus also resulting in tape damage.